Cosmetic creams having the ability to hide wrinkles and other skin imperfections are widely used. Some creams accomplish this task by physical filling of the skin depression, giving the appearance of smooth skin. Another way to hide wrinkles and other skin imperfections is to create a film on the skin surface, which is capable of obscuring the imperfection via light diffusion. According to this method, particles present in the film scatter light producing a diffuse appearance of the underlying skin. Due to this diffuse appearance, the perception of smooth skin is created, and the unwanted skin imperfections are being obscured.
The use of light diffusing pigments for cosmetic applications has been described in Quantification of the Soft Focus Effect, Cosmetics & Toiletries, (Ralf Emmert), vol. 111, pp. 57-61 (1996) (hereinafter, “the Emmert article”). In the Emmert article, the use of silica in light diffusing cosmetics is discouraged due to the similarity of the refractive index of silica (RI=1.46) with that of cosmetic oils (RI=1.45-1.60). Consistent with the Emmert article was the conventional thinking that large differences in refractive index between vehicle and particle were necessary to produce a desired optical effect (i.e., maximum light scattering).
In addition, conventional thinking regarding the use of light diffusing pigments has been to load a composition with light diffusing pigments so as to maximize intra-film light scattering. FIG. 1 illustrates this principle. As shown in FIG. 1, exemplary film 10 comprises a vehicle matrix 11 with light diffusing pigments/particles 12 dispersed therein. When light 13 enters film 10 through upper surface 14, light diffusing pigments/particles scatter light 13 as shown by arrows 15. Given the surface smoothness of upper surface 14 very little light scattering takes place at upper surface 14 relative to an amount of intra-film light scattering that takes place within exemplary film 10.
Efforts continue to develop new approaches for hiding wrinkles and other skin imperfections. Efforts continue to develop obscuring compositions that are easily formulated so as to produce films and coatings that possess desired obscuration properties that are independent of film or coating thickness.